Failure Retry Order in Response to a Network Function Discovery Request

In telecommunications, 5G is the fifth-generation technology standard for cellular networks in which a service area is divided into small geographical areas called cells. The 5G wireless devices in a cell communicate by radio waves with a cellular base station via fixed antennas, over frequencies assigned by the base station.

A 5G network is based on a service-based architecture (SBA), which implements IT network principles and a cloud-native design approach. The core network functions (NFs) of the 5G network are refactored into individual micro-services coming together to automatically discover each other and utilize services offered by each other.

The technologies described herein will become more apparent to those skilled in the art from studying the Detailed Description in conjunction with the drawings. Embodiments or implementations describing aspects of the invention are illustrated by way of example, and the same references can indicate similar elements. While the drawings depict various implementations for the purpose of illustration, those skilled in the art will recognize that alternative implementations can be employed without departing from the principles of the present technologies. Accordingly, while specific implementations are shown in the drawings, the technology is amenable to various modifications.

In a 5G network, an SBA breaks up the core functionality of the 5G network into interconnected NFs, which are typically implemented as cloud-native NFs. The NFs register with a network repository function (NRF) that maintains the states of the NFs. The NFs communicate with each other using the Service Communication Proxy (SCP). The NFs are refactored into individual micro-services, each of which is capable of having multiple instances. With the increasing number of such micro-services, the complexity of service-to-service communications is further increased.

The NRF is a central registry which holds information about every NF in the 5G network. One of the functions of the NRF is service discovery, which is a process of identifying an instance of a service within the 5G network that is capable of fulfilling a service request. Currently, upon receipt of a discovery request associated with the service request from a consumer NF, the NRF checks a database and identifies a list of available service producers from NFs registered with the NRF based on parameters specified by the consumer NF. The consumer NF then sends the service request to an instance of a producer NF identified in the list of available service producers to establish a session. There may be situations in which the instance of the producer NF is unavailable, resulting in failure, error, or timeout of the service request. In such situations, because the NRF in current 5G networks does not provide a retry order for the consumer NF, the consumer NF may retry sending the service request to the same instance of the producer NF, sending the service request to another instance of the producer NF that has similar geo-locality causing the failure, or terminating the service request.

The disclosed technologies address the challenges faced by the consumer NF in current 5G networks by configuring the NRF to include an NF retry order in the list of available service producers such that the consumer NF is able to identify a retry instance of an identified producer NF that is highly likely to succeed in the retry upon a failure of an initial service request to an instance of the identified producer NF. The NF retry order is determined based on one or more factors including at least one of: latency associated with each instance of the producer NF, preference not to retry to the initial instance of the producer NF, capacity associated with each instance of the producer NF, and/or geographic location associated with each instance of the producer NF. Based on the list of available service producers including the NF retry order, the consumer NF can avoid exhaustively trying instances that result in failures.

The description and associated drawings are illustrative examples and are not to be construed as limiting. This disclosure provides certain details for a thorough understanding and enabling description of these examples. One skilled in the relevant technology will understand, however, that the invention can be practiced without many of these details. Likewise, one skilled in the relevant technology will understand that the invention can include well-known structures or features that are not shown or described in detail, to avoid unnecessarily obscuring the descriptions of examples.

is a block diagram that illustrates a wireless telecommunication network(“network”) in which aspects of the disclosed technology are incorporated. The networkincludes base stations-through-(also referred to individually as “base station” or collectively as “base stations”). A base station is a type of network access node (NAN) that can also be referred to as a cell site, a base transceiver station, or a radio base station. The networkcan include any combination of NANs including an access point, radio transceiver, gNodeB (gNB), NodeB, eNodeB (eNB), Home NodeB or Home eNodeB, or the like. In addition to being a wireless wide area network (WWAN) base station, a NAN can be a wireless local area network (WLAN) access point, such as an Institute of Electrical and Electronics Engineers (IEEE) 802.11 access point.

The NANs of a networkformed by the networkalso include wireless devices-through-(referred to individually as “wireless device” or collectively as “wireless devices”) and a core network. The wireless devicescan correspond to or include networkentities capable of communication using various connectivity standards. For example, a 5G communication channel can use millimeter wave (mmW) access frequencies of 28 GHz or more. In some implementations, the wireless devicecan operatively couple to a base stationover a long-term evolution/long-term evolution-advanced (LTE/LTE-A) communication channel, which is referred to as a 4G communication channel.

The core networkprovides, manages, and controls security services, user authentication, access authorization, tracking, internet protocol (IP) connectivity, and other access, routing, or mobility functions. The base stationsinterface with the core networkthrough a first set of backhaul links (e.g., S1 interfaces) and can perform radio configuration and scheduling for communication with the wireless devicesor can operate under the control of a base station controller (not shown). In some examples, the base stationscan communicate with each other, either directly or indirectly (e.g., through the core network), over a second set of backhaul links-through-(e.g., X1 interfaces), which can be wired or wireless communication links.

The base stationscan wirelessly communicate with the wireless devicesvia one or more base station antennas. The cell sites can provide communication coverage for geographic coverage areas-through-(also referred to individually as “coverage area” or collectively as “coverage areas”). The coverage areafor a base stationcan be divided into sectors making up only a portion of the coverage area (not shown). The networkcan include base stations of different types (e.g., macro and/or small cell base stations). In some implementations, there can be overlapping coverage areasfor different service environments (e.g., Internet of Things (IoT), mobile broadband (MBB), vehicle-to-everything (V2X), machine-to-machine (M2M), machine-to-everything (M2X), ultra-reliable low-latency communication (URLLC), machine-type communication (MTC), etc.).

The networkcan include a 5G networkand/or an LTE/LTE-A or other network. In an LTE/LTE-A network, the term “eNBs” is used to describe the base stations, and in 5G new radio (NR) networks, the term “gNBs” is used to describe the base stationsthat can include mmW communications. The networkcan thus form a heterogeneous networkin which different types of base stations provide coverage for various geographic regions. For example, each base stationcan provide communication coverage for a macro cell, a small cell, and/or other types of cells. As used herein, the term “cell” can relate to a base station, a carrier or component carrier associated with the base station, or a coverage area (e.g., sector) of a carrier or base station, depending on context.

A macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and can allow access by wireless devices that have service subscriptions with a wireless networkservice provider. As indicated earlier, a small cell is a lower-powered base station, as compared to a macro cell, and can operate in the same or different (e.g., licensed, unlicensed) frequency bands as macro cells. Examples of small cells include pico cells, femto cells, and micro cells. In general, a pico cell can cover a relatively smaller geographic area and can allow unrestricted access by wireless devices that have service subscriptions with the networkprovider. A femto cell covers a relatively smaller geographic area (e.g., a home) and can provide restricted access by wireless devices having an association with the femto unit (e.g., wireless devices in a closed subscriber group (CSG), wireless devices for users in the home). A base station can support one or multiple (e.g., two, three, four, and the like) cells (e.g., component carriers). All fixed transceivers noted herein that can provide access to the networkare NANs, including small cells.

The communication networks that accommodate various disclosed examples can be packet-based networks that operate according to a layered protocol stack. In the user plane, communications at the bearer or Packet Data Convergence Protocol (PDCP) layer can be IP-based. A Radio Link Control (RLC) layer then performs packet segmentation and reassembly to communicate over logical channels. A Medium Access Control (MAC) layer can perform priority handling and multiplexing of logical channels into transport channels. The MAC layer can also use Hybrid ARQ (HARQ) to provide retransmission at the MAC layer, to improve link efficiency. In the control plane, the Radio Resource Control (RRC) protocol layer provides establishment, configuration, and maintenance of an RRC connection between a wireless deviceand the base stationsor core networksupporting radio bearers for the user plane data. At the Physical (PHY) layer, the transport channels are mapped to physical channels.

Wireless devices can be integrated with or embedded in other devices. As illustrated, the wireless devicesare distributed throughout the network, where each wireless devicecan be stationary or mobile. For example, wireless devices can include handheld mobile devices-and-(e.g., smartphones, portable hotspots, tablets, etc.); laptops-; wearables-; drones-; vehicles with wireless connectivity-; head-mounted displays with wireless augmented reality/virtual reality (AR/VR) connectivity-; portable gaming consoles; wireless routers, gateways, modems, and other fixed-wireless access devices; wirelessly connected sensors that provide data to a remote server over a network; IoT devices such as wirelessly connected smart home appliances; etc.

A wireless device (e.g., wireless devices) can be referred to as a user equipment (UE), a customer premises equipment (CPE), a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a handheld mobile device, a remote device, a mobile subscriber station, a terminal equipment, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a mobile client, a client, or the like.

A wireless device can communicate with various types of base stations and networkequipment at the edge of a networkincluding macro eNBs/gNBs, small cell eNBs/gNBs, relay base stations, and the like. A wireless device can also communicate with other wireless devices either within or outside the same coverage area of a base station via device-to-device (D2D) communications.

The communication links-through-(also referred to individually as “communication link” or collectively as “communication links”) shown in networkinclude uplink (UL) transmissions from a wireless deviceto a base stationand/or downlink (DL) transmissions from a base stationto a wireless device. The downlink transmissions can also be called forward link transmissions while the uplink transmissions can also be called reverse link transmissions. Each communication linkincludes one or more carriers, where each carrier can be a signal composed of multiple sub-carriers (e.g., waveform signals of different frequencies) modulated according to the various radio technologies. Each modulated signal can be sent on a different sub-carrier and carry control information (e.g., reference signals, control channels), overhead information, user data, etc. The communication linkscan transmit bidirectional communications using frequency division duplex (FDD) (e.g., using paired spectrum resources) or time division duplex (TDD) operation (e.g., using unpaired spectrum resources). In some implementations, the communication linksinclude LTE and/or mmW communication links.

In some implementations of the network, the base stationsand/or the wireless devicesinclude multiple antennas for employing antenna diversity schemes to improve communication quality and reliability between base stationsand wireless devices. Additionally or alternatively, the base stationsand/or the wireless devicescan employ multiple-input, multiple-output (MIMO) techniques that can take advantage of multi-path environments to transmit multiple spatial layers carrying the same or different coded data.

In some examples, the networkimplements 6G technologies including increased densification or diversification of network nodes. The networkcan enable terrestrial and non-terrestrial transmissions. In this context, a Non-Terrestrial Network (NTN) is enabled by one or more satellites, such as satellites-and-, to deliver services anywhere and anytime and provide coverage in areas that are unreachable by any conventional Terrestrial Network (TN). A 6G implementation of the networkcan support terahertz (THz) communications. This can support wireless applications that demand ultrahigh quality of service (QOS) requirements and multi-terabits-per-second data transmission in the era of 6G and beyond, such as terabit-per-second backhaul systems, ultra-high-definition content streaming among mobile devices, AR/VR, and wireless high-bandwidth secure communications. In another example of 6G, the networkcan implement a converged Radio Access Network (RAN) and Core architecture to achieve Control and User Plane Separation (CUPS) and achieve extremely low user plane latency. In yet another example of 6G, the networkcan implement a converged Wi-Fi and Core architecture to increase and improve indoor coverage.

is a block diagram that illustrates an architectureincluding 5G core NFs that can implement aspects of the present technology. A wireless devicecan access the 5G network through a NAN (e.g., gNB) of a RAN. The NFs include an Authentication Server Function (AUSF), a Unified Data Management (UDM), an Access and Mobility management Function (AMF), a Policy Control Function (PCF), a Session Management Function (SMF), a User Plane Function (UPF), and a Charging Function (CHF).

The interfaces N1 through N15 define communications and/or protocols between each NF as described in relevant standards. The UPFis part of the user plane and the AMF, SMF, PCF, AUSF, and UDMare part of the control plane. One or more UPFs can connect with one or more data networks (DNs). The UPFcan be deployed separately from control plane functions. The NFs of the control plane are modularized such that they can be scaled independently. As shown, each NF service exposes its functionality in an SBA through a Service Based Interface (SBI)that uses HTTP/2. The SBA can include a Network Exposure Function (NEF), a Network Repository Function (NRF), a Network Slice Selection Function (NSSF), and other functions such as an SCP.

The SBA can provide a complete service mesh with service discovery, load balancing, encryption, authentication, and authorization for interservice communications. The SBA employs a centralized discovery framework that leverages the NRF, which maintains a record of available NF instances and supported services. The NRFallows other NF instances to subscribe and be notified of registrations from NF instances of a given type. The NRFsupports service discovery by receipt of discovery requests from NF instances and, in response, details which NF instances support specific services.

The NSSFenables network slicing, which is a capability of 5G to bring a high degree of deployment flexibility and efficient resource utilization when deploying diverse network services and applications. A logical end-to-end (E2E) network slice has pre-determined capabilities, traffic characteristics, and service-level agreements and includes the virtualized resources required to service the needs of a Mobile Virtual Network Operator (MVNO) or group of subscribers, including a dedicated UPF, SMF, and PCF. The wireless deviceis associated with one or more network slices, which all use the same AMF. A Single Network Slice Selection Assistance Information (S-NSSAI) function operates to identify a network slice. Slice selection is triggered by the AMF, which receives a wireless device registration request. In response, the AMF retrieves permitted network slices from the UDMand then requests an appropriate network slice of the NSSF.

The UDMintroduces a User Data Convergence (UDC) that separates a User Data Repository (UDR) for storing and managing subscriber information. As such, the UDMcan employ the UDC under 3GPP TS 22.101 to support a layered architecture that separates user data from application logic. The UDMcan include a stateful message store to hold information in local memory or can be stateless and store information externally in a database of the UDR. The stored data can include profile data for subscribers and/or other data that can be used for authentication purposes. Given a large number of wireless devices that can connect to a 5G network, the UDMcan contain voluminous amounts of data that is accessed for authentication. Thus, the UDMis analogous to a Home Subscriber Server (HSS) and can provide authentication credentials while being employed by the AMFand SMFto retrieve subscriber data and context.

The PCFcan connect with one or more Application Functions (AFs). The PCFsupports a unified policy framework within the 5G infrastructure for governing network behavior. The PCFaccesses the subscription information required to make policy decisions from the UDMand then provides the appropriate policy rules to the control plane functions so that they can enforce them. The SCP (not shown) provides a highly distributed multi-access edge compute cloud environment and a single point of entry for a cluster of NFs once they have been successfully discovered by the NRF. This allows the SCP to become the delegated discovery point in a datacenter, offloading the NRFfrom distributed service meshes that make up a network operator's infrastructure. Together with the NRF, the SCP forms the hierarchical 5G service mesh.

The AMFreceives requests and handles connection and mobility management while forwarding session management requirements over the N11 interface to the SMF. The AMFdetermines that the SMFis best suited to handle the connection request by querying the NRF. That interface and the N11 interface between the AMFand the SMFassigned by the NRFuse the SBI. During session establishment or modification, the SMFalso interacts with the PCFover the N7 interface and the subscriber profile information stored within the UDM. Employing the SBI, the PCFprovides the foundation of the policy framework that, along with the more typical QoS and charging rules, includes network slice selection, which is regulated by the NSSF.

As discussed above, the NRF is the central registry that holds information about every NF in the 5G network. As the NRF determines suitable NF(s) to fulfill a certain service request, the NRF is also in the position to determine the best alternative NF instances, and the order thereof to retry using the alternative instances, should the initially assigned NF instance encounter a failure.is a flowchart representation of an example signaling sequencebetween a consumer NFand a producer NFin a wireless communication network in accordance with one or more embodiments of the present technology. In this example, a service request is sent based on a list of producer NFs capable of providing a service received by the consumer NFafter sending a discovery request to an NRF. At Operation, the consumer NFsends a discovery request to the NRFto identify a producer NF capable of providing a service to the consumer NF. The discovery request can include information associated with the service the consumer NFplans to request, e.g., parameters defined by the consumer NF, locality information associated with the consumer NF, or network slice information associated with the consumer NF.

At Operation, the NRFsearches a database to identify producer NFs capable of providing the service to the consumer NF. The database stores NF profiles of NFs in the wireless communication network. Upon receiving the discovery request from the consumer NF, the NRFbegins searching for producer NFs that satisfy the parameters defined by the consumer NFin the discovery request. Upon identifying the producer NFs capable of providing the service to the consumer NF, the NRFcan generate a list of the producer NFs. In particular, producer NFs identified in the list of the producer NFs are associated with a retry order identifying an order of retrying a request for the service upon failure of an initial request for the service by the consumer NF. The specific retry order by the NRF, based on factors such as a latency associated with each of the producer NFs identified in the list, provides a higher likelihood of successfully establishing a connection between the NFs with minimal retry overhead, should the initial communication attempt(s) fail. In other implementations, the retry order is further based on factors such as capacity information of instances of the producer NFs identified in the list or geo-location of the instances of the producer NFs identified in the list. At Operation, the NRFsends the list of the producer NFs including the retry order information.

At Operation, the consumer NF, using the list of the producer NFs received from the NRF, sends a service request to instance AA of producer NFidentified in the list. A session is successfully established if the instance AA accepts the service request and sends a corresponding response to the consumer NF. However, in some cases, the instance AA of the producer NFis unavailable to accept the service request. Operationdescribes a situation in which the consumer NFreceives a failure response from the unavailable instance AA. The failure response can include error codes (e.g., 400 client error codes or 500 server error codes) indicating a source of error that resulted in request failure.

At Operation, after receiving the failure response from the instance AA of the producer NFindicating the instance AA is unavailable, the consumer NFreviews the list of the producer NFs received from the NRF. Using the retry order information included in the list of the producer NFs to identify another instance of the producer NF, the consumer NFcan send a service request to the instance BB of the producer NF. Because the retry order is specified by the NRF, the consumer NFdoes not need to obtain information about the producer NFs, such as the load information of the producer NFs and/or specific locality information about the NFs. The consumer NFcan simply rely on the order that is determined based on the NRF's knowledge about the NFs and achieve a higher retry success rate.

At Operation, a session between the consumer NFand the instance BB of the producer NFis successfully established upon accepting of the service request by the instance BB. The instance BB of the producer NFsubsequently sends a corresponding response to the consumer NF.

The consumer NFcan be any of the NFs in the wireless communication network that initiates a service request to another NF in the wireless communication network. For example, the consumer NFcan be an SMF looking to perform online charging. The SMF begins by sending a discovery request to identify CHFs in the wireless communication network capable of performing online charging for the SMF. The discovery request can include identifying information, e.g., type of service request being made by the SMF, that the service being requested is online charging, locality information associated with the SMF, and/or desired parameters for the CHF. Upon receiving the discovery request from the SMF, the NRF searches a database of NF profiles to identify CHFs capable of performing online charging for the SMF.

After identifying the CHFs capable of performing online charging for the SMF, the NRF can be configured to determine a retry order identifying an order of retrying a request for performing online charging by the SMF upon failure of an initial request by the SMF. The NRF can assign different retry orders to each instance of the identified CHFs. The retry order can be based on latency associated with each instance of the identified CHFs. In some implementations, the retry order can further be based on geo-location of each instance of the identified CHFs or capacity information associated with each instance of the identified CHFs.

Based on the search of capable CHFs and determination of the retry order, the NRF can send a list of identified CHFs with retry order information to the SMF. Upon receiving the list, the SMF sends a service request to an instance of a CHF identified in the list to perform online charging. If the initial service request fails, the SMF can send a service request to another instance of the CHF based on the retry order information included in the list of identified CHFs.

is a block diagram that illustrates a service request made by a consumer NFbased on a list of producer NFs capable of handling the service request and a retry order received from an NRF. Upon receiving a list of producer NFs capable of handling the service request, the consumer NFcan initiate a service request to instanceA of producer NF. As shown in, the producer NFis in a multi-endpoints configuration and includes four instancesA-D. Each instance of the producer NFis part of an NF set capable of handling the service request by the consumer NFbecause instances of the producer NFin the NF set share a database. The instances of the producer NFcan be divided into multiple sites, such that Site() includes instancesA andB, whereas Site() includes instancesC andD.

In an example, the consumer NFsends a service request to instanceA of the producer NFand receives a failure response indicating the instanceA is unavailable to provide the service. Upon such failure, the consumer NFcan retry sending the service request to another instance of the producer NFwhich is available to provide the service to the consumer NF. The list of producer NFs capable of handling the service request corresponds to a retry order associated with each instance of the producer NF. For example, the retry order indicates an instanceC that has a high likelihood of successfully establishing a connection. Based on the retry order, the consumer NFsends a subsequent service request to instanceC such that a connection can be established successfully with minimal retry overhead.

In some implementations, the instances of the producer NFare categorized into NF sets. In some embodiments, instances within the same NF set are located, or considered to be co-located, in the same site. For example, the NRFcan identify instancesA andB as part of NF setand instancesC andD as part of NF set. The NRFcan determine, based on its knowledge of the NFs, that if the initial request for service to instanceA fails, Site() can be problematic for establishing connections for such service. Accordingly, the NRFcan specify a retry order indicating that instancesC andD are preferred retry instances by deliberately avoiding possible errors or failures caused by Site(). Such retry order provided by the NRFcan result in higher likelihood of establishing a successful retry after failure of an initial request by the consumer NF. Using the retry order information received from the NRF, the consumer NFcan retry sending the service request to instanceC orD of the NF setbefore retrying to instanceB, so as to increase the success rate of retry and reduce any overhead cost associated with the retry process.

In some implementations, the NRFcan group instances of the producer NFbased on latency associated with each instance of the producer NF. For example, the NRFcan identify instancesB andC as NF setand instanceD as part of NF set, based on determining that instancesB andC are associated with low latency and instanceD is associate with high latency. The NRFcan set a predetermined threshold for latency to group the instances. Instances with latency below the predetermined threshold can be identified as part of NF set, and instances with latency above the predetermined threshold can be identified as part of NF set.

Alternatively or additionally, the grouping of instances of the producer NFby the NRFis based on a CPU utilization associated with each instance of the producer NF. Instances with CPU utilization above the threshold are less likely to establish a successful retry after failure of an initial request by the consumer NFas compared to instances with CPU utilization below the threshold. The NRFcan set a CPU utilization threshold such that instances with CPU utilization below the threshold are identified as part of NF set, and instances with CPU utilization above the threshold are identified as part of NF set. In some implementations, the NRFdynamically updates the retry order based on one or more factors including, but not limited to, thresholds associated with latency or CPU utilization of each instance of the producer NF.

is a flowchart representation of an example processfor identifying a list of producer NFs including a retry order in accordance with one or more embodiments of the present technology. Other implementations of the processinclude additional, fewer, or different steps or performing the steps in different orders.

At Operation, an NRF of a wireless communication network receives a discovery request from a consumer network node to identify a producer network node capable of providing a service. The discovery request identifies parameters defined by the consumer network node and can include information of the service request by the consumer network node, locality information associated with the consumer network node, or network slice information associated with the consumer network node. The consumer network node can be any network node in the wireless communication network that can communicate with and make a service request to other network nodes in the wireless communication network. For example, the consumer network node is an SMF making a request to a CHF to perform online charging. In another example, the consumer network node is a PCF making a subscribe request to a CHF. As explained in the examples, a network node serving as a consumer network node in one example process can serve as a producer network node that provides a service to another network node in another example process.

At Operation, in response to the discovery request, the NRF determines producer network nodes capable of providing the service to the consumer network node. The producer network nodes are identified by accessing a database that includes profiles of network nodes in the wireless communication network.

At Operation, the NRF determines a retry order identifying an order of retrying a request for service upon failure of an initial request for service. The NRF can be configured to identify a retry order for at least one producer network node such that the retry order indicates another producer network node to retry the request for service. In some implementations, the producer network nodes identified by the NRF are associated with multiple instances, each instance associated with a single producer network node belonging to a same network node group. In other implementations, instances associated with the producer network node belongs to different network node groups. The NRF can be configured to identify, for each instance of the producer network node identified by the NRF, the retry order that specifies another instance or a group of instances of the producer network node to retry the request for service upon failure of an initial request for service. In some implementations, the NRF is configured to assign the multiple instances of the identified producer network node into different retry groups. The different retry groups are defined by the NRF to indicate a preferred retry group of instances to retry to in an event of request failure associated with a given instance of the identified producer network node. Assignment of the retry groups can be based at least on a latency associated with each instance of the multiple instances.

At Operation, the NRF sends information about a list of producer network nodes capable of providing the service to the consumer network node. The list can include a number of instances associated with each of the producer network nodes and the retry order identifying an order of retrying a request for service upon failure of an initial request for service. For example, in response to a discovery request by an SMF to identify CHFs capable of providing online charging services for the SMF, the NRF sends a list of CHFs to the SMF. The list of CHFs can include information such as network node group information, retry group information, and retry order information associated with each instance of the CHFs in the list.

is a flowchart representation of an example processfor sending a retry request for service upon failure of an initial request for service by a consumer network node. At Operation, a consumer network node of a wireless communication network sends a discovery request to an NRF to identify a producer network node capable of providing a service. The discovery request identifies parameters defined by the consumer network node and can include information of the service request by the consumer network node, locality information associated with the consumer network node, or network slice information associated with the consumer network node. The consumer network node can be any network node in the wireless communication network that can communicate with and make a service request to other network nodes in the wireless communication network.

At Operation, the consumer network node receives information from the NRF about a list of producer network nodes capable of providing the service to the consumer network node. The list can include multiple producer network nodes capable of providing the service, a number of instances associated with each of the producer network nodes, and the retry order identifying an order of retrying a request for service upon failure of an initial request for service.

At Operation, the consumer network node, after sending an initial request to a producer network node identified in the information received from the NRF, receives a failure response. Failure can be due to various reasons, including, but not limited to, errors associated with the producer network node, problems with the initial request due to errors such as incorrect syntax or absence of permission, and/or problems associated with the wireless communication network.

Upon failure of an initial request for service, the consumer network node, at Operation, sends a retry request to another producer network node identified in the list of producer network nodes. The list of producer network nodes can include a retry order associated with each producer network node in the list such that the consumer network node is enabled to determine a next preferred producer network node to retry the request to upon failure of an initial request.

In some implementations, the list further includes network node group information associated with each of the producer network nodes. The producer network nodes can be categorized into different network node groups based on factors including, but not limited to, latency information, capacity information, and/or geo-location information associated with the producer network nodes.